It was the experience of mystery - even if mixed with fear - that engendered religion.

All the fifty years of conscious brooding have brought me no closer to answer the question, "What are light quanta?" Of course today every rascal thinks he knows the answer, but he is deluding himself.

What I seek to accomplish is simply to serve with my feeble capacity truth and justice, at the risk of pleasing no one.

It is the same with people as it is with riding a bike. Only when moving can one comfortably maintain one's balance.

One should not pursue goals that are easily achieved. One must develop an instinct for what one can just barely achieve through one’s greatest efforts.

I have little patience with scientists who take a board of wood, look for its thinnest part, and drill a great number of holes where drilling is easy.

Mankind must give up war in the Atomic Era. What is at stake is the life or death of humanity.